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The chemical composition of β Cephei and hybrid pulsators in the solar neighbourhood

Published online by Cambridge University Press:  27 October 2016

Norbert Przybilla
Affiliation:
Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstr. 25/8, A-6020 Innsbruck, Austria email: norbert.przybilla@uibk.ac.at, maria-fernanda.nieva@uibk.ac.at
Maria-Fernanda Nieva
Affiliation:
Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstr. 25/8, A-6020 Innsbruck, Austria email: norbert.przybilla@uibk.ac.at, maria-fernanda.nieva@uibk.ac.at
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Abstract

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β Cephei variables are the most prominent pulsators among the massive stars on the upper main sequence, extending into the class of the rare hybrid β Cephei-SPB pulsators in the overlap region with the instability strip of the Slowly Pulsating B-stars. While the κ-mechanism has been identified as the driver of the pulsations, a comprehensive explanation of the excitation of the observed p- and g-modes is still lacking. In particular, the instability regions for these main-sequence B-type pulsators are still not fully consistent with any current opacity calculations. We have determined tight observational constraints on the chemical composition of a sample of β Cephei and hybrid pulsators in the solar neighbourhood, covering all elements with abundances log (X/H) + 12 > 7.3. The star sample turns out to be chemically homogeneous, with a metallicity Z ≈ 0.014 and a non-solar abundance mix. The availability of accurate and precise abundances eliminates one of the two variables in the opacity calculations for asteroseismic applications, allowing to focus on (missing) atomic data.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2016 

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